The received wisdom is that American choreographers like Martha Graham and Merce Cunningham gave the world modern dance, that they inscribed its language, forged its aesthetic and created its key texts. In fact, the work of the American pioneers was paralleled by that of German Expressionist dance-makers like Kurt Jooss, and this school would produce a choreographer who, more than any American, would define the psychological landscape of contemporary dance.

Pina Bausch was born in 1940 and studied and danced under Jooss. In 1973, she launched her own company in the nondescript German city of Wuppertal and since then has produced a body of work unique in its dark power and imaginative scale. The pieces are surreal and dreamlike, intensely detailed in construction, and often last for hours. In Arien (1979), the evening-dressed cast is discovered lying in ankle-deep water. In Nelken (1992), women roam a stage carpeted with carnations and patrolled by Alsatian guard dogs. Central to all of Bausch's pieces is the traumatised interplay of its performers, who often seem caught in conflicting dreams. There are excruciating spoken confessions, anguished physical and emotional self-barings, babbling litanies of personal detail.

Many of these tropes are evident in Café Müller (1978), the first of two pieces shown at Sadler's Wells. The half-hour work, set to snatches of music by Henry Purcell, sees a series of characters sleepwalking in and out of a deserted cafe. Characteristically, there is a sense that they are refugees from some long-terminated event. Trapped in an existential tape loop, they endlessly reprise their actions and interactions.

There's a hawk-faced man in a suit who enters and exits with blank purpose; an anguished waiter endlessly clearing away the furniture; a blind woman caught in a revolving door; and a couple who attempt mutual support but end up battering each other against the wall. Perhaps they are all already dead: their hopeless, desolated faces certainly suggest this.

Overlaying the melancholy, meanwhile - so delicate as to be near-invisible - are passages of exquisite, minimal dance. Arms extended in sad, imploring farewell, bodies swaying as if animated by some faint, underwater current. The result is as uplifting as it is intensely sad, and shot through with a haunting familiarity. It's a mistake to try and decode Bausch pieces; they're too elusive for that, but Café Müller seems to be a digest of childhood memories. Bausch's parents owned a cafe and the giant doors suggest a child's perspective. And who knows what impression of adult relationships may have been formed by a child born in Germany in 1940?

The evening's second piece is Bausch's 1975 version of The Rite of Spring. Stark and grim, set on a blank stage carpeted in soil, it shows the selection and death of a sacrificial victim. The circumstances are enigmatic, but there is a pointed contrast between the muscled phalanx of men who make the selection and the cowering ranks of women who provide the victim. There is an implicit sense of rape and, interlaced with the pounding fury and self-hatred, a whisper of the nightmare worlds of Belsen and Treblinka. Ruth Amarante, the victim, almost seems to dissolve with terror.

Although Café Müller and The Rite of Spring are celebrated pieces, each has been seen only once in the UK before (in Edinburgh) and this is only Tanztheater Wuppertal's fifth visit to London. Bausch was billed to perform in Café Müller, but in the event was indisposed. All of which, as a standing ovation proved, leaves us wanting more.

The Bausch programme apart, it was an event-packed week for contemporary dance, with both Rafael Bonachela and Diversions (the Dance Company of Wales) enjoying rapturous receptions at the Queen Elizabeth Hall. Bonachela's piece, although occluded by over-aggressive music and effects, was his strongest ever, and Diversions' 25th anniversary season saw the company on thundering, Amazonian form. On the dance stage, as on the rugby field, never underestimate the Welsh.